超级双相不锈钢S32750轧制开裂原因分析和解决措施

Reason analysis and solution of rolling cracking of super duplex stainless steel S32750

S32750钢属于耐腐蚀超级双相不锈钢,某批次的管材轧制过程中出现严重的开裂。运用光谱仪、光学显微镜、扫描电镜、拉伸试验机和冲击试验机等设备,结合轧制工艺和热挤压工艺,对材料的化学成分、非金属夹杂物、显微组织和力学性能进行了分析。结果显示,轧制前组织中存在大量Fe⁃Cr⁃Mo聚集的σ金属间相,脆性大,导致锻轧钢管开裂;锻轧前采用1100℃×60 min固溶处理后,σ金属间相充分溶解,强度、硬度降低,塑韧性提高,可解决锻轧开裂问题。

Serious cracking occurred in the rolling process of a batch of pipes made of S32750 super duplex stainless steel.The chemical composition,non⁃metallic inclusions,microstructure and mechanical properties of the pipe materials were analyzed by means of spectrograph,metallographic microscope,scanning electron microscope,tensile tester and impact tester,and combined with rolling process and hot extrusion process.The results show that there are a lot ofσ⁃intermetallic phases with Fe⁃Cr⁃Mo segregation in the microstructure before rolling,which is brittle and leads to cracking of the rolled steel pipe.After solution treatment at 1100℃for 60 min before rolling,the intermetallic phaseσis fully dissolved,the strength and hardness are reduced,while the plasticity and toughness are improved,which can solve the rolling cracking problem.